Ricoh Company, Ltd.

Dai Nippon Printing Co., Ltd.

Hitachi Koki Co., Ltd.

Asahi Kasei Chemicals Corporation

Ricoh Printing Systems, Ltd.

Tsutomu Nakagawa

Yoshitaka Fujinuma

Susumu Tateyama

Masayoshi Nakayama

Koji Kato

Takashi Suzuki

Tatsuya Kubo

Tomonari Hokkyo

Teruaki Mitsuya

Keisuke Kubota

Masayasu Anzai

Kenji Nozawa

Yasuo Takuma

Tsuneaki Kawanishi

Shinichi Akatsu

Hisao Okada

Masayuki Ainoya

Masato Miwa

Yuichiro Suzuki

Katsuya Kawai

Hiroyoshi Matsumoto

Shigeru Tosa

Tohru Sugiyama

Naonori Higashimoto

A development apparatus includes a first developer chamber configured to store and supply the developer, a first developer bearer configured to convey the developer supplied from the first developer chamber to a first development domain, defined by a portion of the first developer bearer facing a latent image bearer, to develop the latent image, a second developer bearer configured to convey the developer passed through the first development domain to a second development domain, defined by a portion of the second developer bearer facing the latent image bearer, to develop the latent image, a second developer chamber configured to recover the developer passing through the second development domain and store the recovered developer, and a transfer prevention member provided between the second developer chamber and the second developer bearer to reduce a transfer of the developer from the second developer chamber to the second developer bearer.

Development apparatus having two developer bearers and two development chambers

An image formation apparatus is disclosed. The image formation apparatus includes a transfer effectiveness detector that further includes a computing unit for converting a sensor output voltage into a toner adhesion amount, and a transfer effectiveness detecting unit for obtaining transfer effectiveness by comparing a toner adhesion amount Td on a photo conductor with a toner adhesion amount Tb on a middle transfer object. Here, the toner adhesion amount Td is obtained by the computing unit converting an output of a photo conductor image detection unit, and the toner adhesion amount Tb is obtained by the computing unit converting an output of a middle transfer object image detection unit. When the transfer effectiveness detection unit determines that an abnormality is present in the transfer, whether the abnormality is due to decreased development capacity or due to decreased transfer effectiveness can be determined. If it is determined that the transfer effectiveness is less than a threshold value, a printing operation of the image formation apparatus is stopped given that the transfer effectiveness compensation is not possible.

Image formation apparatus

In a developing device, a receive-convey screw conveys a developer received from a developer carrier. The receive-convey screw includes a receive-convey blade including a lower, outer circumferential end located in a downstream end of the receive-convey blade in the developer conveyance direction of the receive-convey screw. A slant-convey screw is disposed obliquely relative to an axial direction of the receive-convey screw, and conveys the developer received from the receive-convey screw upward. The slant-convey screw includes a slant-convey blade including a lower, outer circumferential end located in an upstream end of the slant-convey blade in the developer conveyance direction of the slant-convey screw, the lower, outer circumferential end being located at a height level lower than the lower, outer circumferential end of the receive-convey blade.

Image forming apparatus and developing device

An image formation system is configured by connecting two or more image formation devices. The system includes a fixing device fixing an unfixed development image to a record medium and a charge elimination device eliminating a charge of the record medium in an inlet of the fixing device of the second or later image formation device.

Image forming system having charge balancing system

A water-absorbing resin has a polymer molecular chain in which 50 mol % or more of repeating units in the chain are carboxy group-containing units, wherein the carboxy group neutralization ratio in the central part of the resin is 60 mol % or more and the carboxy group neutralization ratio on the external surface of the resin is 50 mol % or less. A method for producing the water-absorbing resin comprises polymerizing a monomer solution to form a polymer, drying the resulting polymer, and heat-treating the dried polymer, wherein the monomer solution contains a mixture comprising an alkali metal salt of an unsaturated carboxylic acid and an ammonium salt thereof, the percentage of the ammonium salt being more than 50 mol % of the mixture, and further contains a condensation crosslinking agent.

Water-absorbent polymer and process for producing the same

A developing device includes first-third sections, a developing roller, a partitioning wall and a toner concentration detector. The first-third sections have first-third screw augers respectively. The partitioning wall isolates the third section from the first section and the second section. A supply opening is formed in a portion of the partitioning wall opposing the first section. A toner concentration detector is disposed in the third section. The first screw auger conveys developer including toner to the developing roller, into the third section via the supply opening, and into the second section. The second screw auger conveys developer accommodated in the second section into the third section. The third screw auger conveys developer accommodated in the third section into the first section. Toner is replenished into the third section based on a detection result by the toner concentration detector.

Developing device in image-forming device

The white chromaticity, in which the illumination environment is considered, is measured for each individual color monitor (). A reference body (Q), comprising a perfect diffuser, is applied on the screen of the color monitor (). By a test pattern display means (), a test pattern (T) is displayed on the screen of the color monitor () based on tone values of the three primary colors R, G, and B that are stored in a tone value storage means (). While fixing the tone value of the primary color R at 255, the tone values of the primary colors G and B are varied cyclically from 0 to 255 in a prescribed period by a tone value varying means (). An operator inputs the result of comparing the color of the test pattern (T) and the color of the reference body (Q). When a comparison result indicating the matching of the two is input, a comparison result entering means () outputs an agreement signal. A measurement result output means () outputs, as the measurement results indicating the white chromaticity based on the reference body (Q), the tone values of the three primary colors R, G, and B that are stored in the tone value storage means () at the point at which the agreement signal is provided.

Color monitor white chromaticity measuring device

A fixing device wherein supposing that the total load given to a heating roller and a pressure roller is W (kgf) and the area of the pressure contact portion of the heating roller with respect to the pressure roller (nip area) is S (cm), the nip pressure (=W/S) is 2.7 kgf/cmor more and the length of the pressure contact portion in the direction parallel to the direction of conveyance of a recording material is defined to be 14 mm or more.

Fixing device including heating roller and pressure roller

A uniform image is obtained by matching the sliding friction force, the moving speed and the developing agent in a developing region of two developing rollers and an electric characteristic of a photosensitive body used for image development. Two developing rollers rotating in directions opposite to each other are used, the moving direction of the first developing roller being opposite to the moving direction of the photosensitive body, and a circumferential speed ratio of a circumferential speed of the first developing roller to a circumferential speed of the photosensitive body is within a rage of 0.5 to 2.5; and the moving direction of the second developing roller is equal to the moving direction of the photosensitive body, and a circumferential speed ratio of a circumferential speed of the second developing roller to a circumferential speed of the photosensitive body is within a range of 1.5 to 3.5. A ratio of the sliding friction force between a magnetic brush for developing agent and the photosensitive body formed in the first developing roller and the sliding friction force between a magnetic brush for developing agent and the photosensitive body formed in the second developing roller is within a range of 0.9 to 2.1.

Electrophotographic apparatus

Growing community of inventors

Tokyo, Japan

Tsutomu Nakagawa